Various work environments present explosion risks associated with the utilized materials and operating conditions. Paint spraying and other mixing and chemical operations can produce flammable fumes and other suspended flammable material, creating particular hazards in this regard. In response to these safety concerns, it is often preferable to utilize compressed air to drive mechanical devices in such environments, for example, rotary disk sprayers for paint atomization, rather than using electrically driven devices which can spark and cause an explosion. The compressed air used to drive such devices decompresses and expands as it performs the desired work, transferring kinetic energy to the driven device. However, depressurization of the compressed air to ambient (typically atmospheric) pressure allows a substantial increase in volume as the air exits the pressurized system, and a concomitant drop in the temperature of the air. As the air cools, it can absorb heat energy from the ambient surroundings. In many cases, the air absorbs a substantial amount of heat from the air-driven component and the surrounding housing, reducing their temperatures below the ambient dew point, which causes water condensation on the equipment Where the change in pressure is sufficient, the temperature of the equipment may be reduced enough to actually freeze the condensed water.
Condensation causes a variety of problems that are preferably avoided. Condensation may speed corrosion of the equipment, adversely affecting the life expectancy of expensive equipment and adversely affecting its accuracy or efficiency. Worse, corrosion can disrupt the integrity of the process, or require process downtime to allow water or even ice to be removed from the equipment.
For example, in high-speed, high-quality paint processes, such as in the paint booths utilized by many automobile manufacturers, a single drop of water can ruin a paint job on an automobile. Existing designs have attempted to overcome the condensation issue by heating the compressed air remote from the workspace so that when it decompresses, the air does not cool to the ambient dew point. However, because of the low thermal capacity of air, such systems have met with only limited success. The heating element in such systems is typically electrical and must be kept remote from the air-driven device. Since air loses its thermal energy rapidly to ambient conditions, any distance the air travels beyond a few inches results in greatly reduced compressed air temperature, and thus a significant reduction in the efficacy of heating the air.